1. Field of the Invention
The field of the present invention is drive axle assemblies and more particularly, drive axle assemblies commonly used in trucks.
2. Discussion of Related Art
Many trucks have a drive axle assembly which includes a gear housing provided by an integral axle housing. The gear housing has a front opening to allow for connection of its input shaft with an exterior yoke or flange which is in turn connected with a drive shaft of the vehicle. The input shaft powers a pinion gear which is meshed with a ring gear. The ring gear is connected with a differential carrier. The carrier is connected with a spider having spider gears rotatively mounted thereon. The spider gears are meshed with opposing side gears. The side gears are connected with two side journals or half shafts. The half shafts extend laterally outward from the gear housing to drive the drive wheels of the vehicle. The gear housing is either integral with or fixably connected with an axle housing. The axle housing encloses the half shafts.
The gear housing has an opening to allow for the insertion of the various components of the differential gear set. An enclosure member is provided to close the opening. The enclosure member and gear housing provides a lubricant reservoir, which is commonly filled with oil. The function of the oil is to lubricate the primary gearing, differential gear set and associated bearings. Oil is allowed to flow through the axle housings and also to lubricate the half shaft bearings which are most adjacent to the connected wheels. The rotation of the ring gear causes the lubricant to be circulated within the gear housing.
Various contaminants can be present within the lubricant. Foundry sand may be present due to insufficient cleaning of the housing before the axle assembly operation. Working of the various gears within the gear housing can cause particles of metal to be produced within the lubricant. Such particles can cause undesirable wear upon the gear train and inhibit the proper flow of lubricant throughout the axle assembly.
Another consideration in the design of drive axle assemblies is to reduce the temperature of the lubricant to maximize the lubricant's effective life. The churning of the lubricant within the reservoir by the ring gear causes the lubricant temperature to rise. To cool the lubricant it is desirable that as much lubricant as possible passes out of the gear housing and into the arms of the axle housings or in the suspension within the gear housing atmosphere. Movement of lubricant into the axle housing arms is also desirable to ensure proper lubrication for the inboard and outboard bearings that support the half shafts.
To maximize fuel efficiency of the vehicle it is desirable to reduce vehicular weight. Therefore it is desirable to provide a drive axle assembly housing wherein the mass of lubricant within the axle housing can be held to a minimum and reduce component churning efficiency loss that will reduce energy consumption.